Note that this might not always give you the latest stable Tor version, but
you will receive important security fixes. To make sure that you're running
the latest stable version of Tor, see option two below.

Now Tor is installed and running. Move on to step two of the "Tor on Linux/Unix"
instructions.

Do not use the packages in Ubuntu's universe. In the past they have
not reliably been updated. That means you could be missing stability
and security fixes.

Raspbian is not Debian. These packages will be confusingly broken
for Raspbian users, since Raspbian called their architecture armhf but
Debian already has an armhf. See this
post for details.

You'll need to set up our package repository before you can fetch
Tor. First, you need to figure out the name of your distribution. A
quick command to run is lsb_release -c or cat /etc/debian_version.
If in doubt about your Debian version, check the Debian website.
For Ubuntu, ask Wikipedia.

I run
and want
version

You need to add the following entry in /etc/apt/sources.list or a new file in /etc/apt/sources.list.d/:

deb http://deb.torproject.org/torproject.org wheezy main

Then add the gpg key used to sign the packages by running the following commands at your command prompt:

We provide a Debian package to help you keep our signing key current. It is
recommended you use it. Install it using

apt-get install deb.torproject.org-keyring

To finally install Tor just run:

apt-get install tor

Now Tor is installed and running. Move on to step two of the "Tor on Linux/Unix"
instructions.

The DNS name deb.torproject.org is actually a set of independent
servers in a DNS round robin configuration. If you for some reason cannot
access it you might try to use the name of one of its part instead. Try
deb-master.torproject.org,
mirror.netcologne.de or
tor.mirror.youam.de.